Diffusion-weighted image and MR spectroscopic analysis of a case of MELAS with repeated attacks
Hyun Sook Kim ; Dong Ik Kim ; Yong Kyu Yoon ; Seung Hyung Kim ; Eun Ju Kim ; Pyeong Ho Yoon ; Jong Doo Lee ; Chulhee Choi ; Eun Kee Jeong ; Byung In Lee
Yonsei Medical Journal, Vol.42(1) : 128~133, 2001
Yonsei Medical Journal
We report the clinical and MR manifestations of an 18 year-old girl with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome. Recurrent status epilepticus caused reversible cytotoxic edema on diffusion-weighted images (DWI). Initial and one month follow-up MR spectroscopy, after seizure control, showed some discrepancies in the ratio of metabolites. N-acetylaspartate (NAA) partially recovered (NAA/creatine (Cr) ratio: 1.27→1.84). This was because of a normalization of decreased NAA due to cellular dysfunction as a result of status epilepticus. A low ratio of NAA/Cr due to abnormal mitochondria remained in the decreased state. Reversible NAA/Cr ratios in the acute lesion suggested that NAA reflects the neuronal function as well as the level of neuronal structural damage. The altered NAA/Cr ratio better correlated with the abnormal signal intensity area of T2-weighted images (T2WI) and DWI than the lactate (Lac)/Cr ratio. With conservative treatment with anti-epileptics not accompanied by coenzyme Q or sodium dichloroacetate, lactate persistently increased (Lac/Cr ratio: 1.01→1.21) because of the continued production of lactate in cells with respiratory deficiency, which is the main pathology of MELAS.